Professor Cozmo leaves either with Team Aqua or Team Magma (Team Magma in Pokémon Emerald) for the Meteor Falls, thinking that they are going to help him excavate meteors. However, the offending Team steals the meteorite, intending to use it to power their machine at Mt. Chimney. After defeating the grunts and the team's leader, the player can take the meteorite from the machine and return it to the Professor in exchange for TM27 (Return).

In the anime
In Fight for the Meteorite, Professor Cozmo meets Ash Ketchum on Mt. Chimney. The situation from there is similar to in the games. He is voiced by 西村朋紘 Tomohiro Nishimura in Japanese.

In the Pokémon Adventures manga

In the Chuang Yi translation of the fourth chapter, he is referred to as Professor Starstone. This error is rectified when he appears in a flashback during the fifth chapter.

Professor Cozmo believed Team Aqua to be noble heroes, so he assisted them with the meteor and their device on Mt. Chimney.